Glass disc for telescope mirror, 12" diameter and 2 1/4" thick. Built up from two 3/8" plate glass circles separated by granulated glass in an experiment conducted by Sir Charles A. Parsons
Glass disc for telescope mirror, 12" diameter and 2 1/4" thick. Built up from two 3/8" plate glass circles separated by granulated glass in an experiment conducted by Sir Charles A. Parsons